Be sure that the chimney is clear of any nests from birds, squirrels or other animals.

Check flue damper operation. Make sure it opens and closes fully, and that it is able to be locked in the open or closed position.

Check chimney draft. Make sure the chimney will draw up the fire and smoke properly. Test this by taking several sheets of newspaper and rolling them up. Then with the fireplace damper in the open position, light the newspaper in the fireplace. The smoke should rise up the chimney. If it doesn't, you have an obstruction and need to call a professional in to clean the chimney of creosote and ash and possible debris.

Also, have the fire brick in the fireplace inspected. If you see any open mortar joints have them repaired immediately! A fire can spread into the stud wall behind the masonry fire brick through open mortar joints.